1. Field of the Invention
The present invention relates to a gas cylinder used in a table, a chair, or the like, and more particularly to a structure which can firmly fixes the outer tub of the gas cylinder and a support plate with a low cost.
2. Description of the Prior Art
A conventional gas cylinder includes a spindle 20 which can be slidably moved along the inner surface of a tube guide 30 surrounded by an outer tub 100 in the same axis as the outer tub as shown in FIG. 1. A piston rod 15 connected to the spindle is fixed to a support plate 50 fixed to an end of the outer tub. A piston 10 which is fixed to one end of the piston rod so as to be slidably moved upward and downward by regulating a hydraulic pressure is installed in the spindle 20.
The above-mentioned gas cylinder fixes a sitting member of a table plate or a chair to the upper end portion of the spindle, and a support member is inserted into a lower portion of the outer tub.
Therefore, the load applied to the spindle is applied to a support plate 50 connected to the piston rod. A cushion rubber 36, a ball bearing 45 interposed between bearing support 40a and 40b are inserted into an end portion of the piston rod 15 to reduce the rotational frictional force of the spindle. The end portion of the piston rod into which the bearing support is inserted is fixed to a support plate 50 by using a clip 47.
The conventional structure in which the end portion of the outer tub 100 and the support plate 50 are fixed has an embossing as describe in U.S. Pat. No. 4,969,616 so that the support plate 50 is caught in the inner wall of the outer tub 100. A rim extended at the embossing portion is curled towards the support plate 50.
Further, a structure in which an end of an outer tub is embossed by making the shape of the support plate 50 and the lower end of the outer tub is curled as shown in FIG. 2 and a structure in which an uneven support plate 50 of inserted into an outer tub 100 and a support plate 50 and an outer tub 100 are embossed and the curling is omitted as shown in FIG. 3 have been suggested.
The above-mentioned structure was suggested to settle the problem by which the manufacturing processes are complex and the assembling cost is expensive. However, the shape of the embossing 60 is deformed when the rim 65 is curling and the support plate 50 is fixed. In the result, the shaking of the support plate is generated and the support plate is deformed.
The present invention has been made to solve the above-mentioned problem, and accordingly it is an object of the present invention to provide a structure which can firmly fixes the outer tub of the gas cylinder and a support plate with a low cost.
In order to achieve the above-mentioned object, the present invention provides a gas cylinder in which one end of a piston rod extending to the inner side of an outer tub is fixed to a support plate fixed to one end of the outer tub and a spindle connected to the other end of the piston rod is slidably moved along the piston rod in a same axis direction as the outer tub and an outer tub support plate fixing structure of a gas cylinder wherein a plurality of first and second pieces are formed along the end surface of the outer tub and a protruding portion is formed on the inner side of the outer tub and the support plate is positioned so as to make contact with the protruding portion and the support plate is fixed to the second piece is formed.
The protruding portion is formed by bending the first piece and the second piece is fixed so as to surround the support plate by curling the second piece towards the inner side of the outer tub.
The width of the first piece is equal to or smaller than the width of the second piece.
The width of the first piece is larger than the width of the second piece.
The diameter of the support plate is smaller than the diameter of the outer tub.